1. Field of the Invention
The present invention relates to novel pyranobenzoxadiazole derivatives, pharmaceutical compositions containing said derivatives, use thereof for the therapy of hypertension or asthma which causes in mammarian animals inclusive of human being and a process for producing the above.
2. Description of the Prior Art
Japanese Patent Laid-open Publication No. Sho 58-67683 (67683/1983) discloses that a compound (Development code No. BRL-34915) of the formula (A): ##STR2## has an activity for lowering blood pressure with respect to spontaneously hypertensive rats.
Br. J. Pharmac. (1986), 88, p.p. 103-111 discloses the possibility that the compound BRL-34915 activates K.sup.+ channel and moves resting potential of membrane to the hyper polarization.
Br. J. Pharmac. (1986), 89, p.p. 395-405 shows that the compound BRL-34915 loosens trachealis of guinea pig and suggests that it has utility as a medicine for the therapy of asthma.
Angiology (1987), 27, pp. 425-431 suggests that a composition for activating K.sup.+ channel is effective for the treatment of arrhythmia and angina pectoris.
Br. J. Pharmac. (1987), 91, pp. 803-813 shows that the compound BRL-34915 loosens uterus of rats. For this fact, it may be effective for preventing premature delivery.
DLO News ROUND-UP No. 312 (1987) shows that the compound BRL-34915 is effective for the medical treatment of incontinence and pain.
However, EP-A-28449 and EP-A-28064 shows that the benzopyran derivatives to which the BRL-34915 belongs may undesirably affect the action of the heart.
As the result of the intensive research of novel compounds, therefore, the present inventors have found out that novel pyranobenzoxadiazole derivatives have strong activity for lowering blood pressure. Then, the present inventors have accomplished the present invention.